D = ('a' .. 'z').to_a - ['n']
N = gets.to_i
prefix = (1 .. N - 1).map do |i|
  s = i
  q = []
  until s == 0
    s,m = s.divmod(D.size)
    q << D[m]
  end
  "a#{q.join}a"
end
prefix << 'an'
puts prefix